FUNDAMENTALS of SPUN YARN TECHNOLOGY Carl A. Lawrence, Ph.D. CRC PRESS Boca Raton London New York Washington, D.C. © 2003 by CRC Press LLC Library of Congress Cataloging-in-Publication Data Lawrence, Carl A. Fundamentals of spun yarn technology / Carl A. Lawrence. p. cm. Includes bibliographical references and index. ISBN 1-56676-821-7 (alk. paper) 1. Spun yarns. 2. Spun yarn industry. 3. Textile machinery. I. Title. TSI480.L39 2002 677′.02862—dc21 2002034898 CIP This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. 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Visit the CRC Press Web site at www.crcpress.com © 2003 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 1-56676-821-7 Library of Congress Card Number 2002034898 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper Dedication to Mary © 2003 by CRC Press LLC Preface The fundamentals of spun-yarn technology are concerned with the production of yarns from fibers of discrete lengths and the structure-property relation of the spun yarns. Ever since humans moved from using the skins of hunted animals for clothing to farming and using farmed animal hairs and fibers from nonfood crops, and eventually to the manufacture of synthetic fibers, the spinning of yarns has been of importance to (initially) the craft and (subsequently) the science, design, and engi- neering of textiles. This book is aimed at giving the reader a good background on the subject of the conversion of fibers into yarns, and an in-depth understanding of the principles of the various processes involved. It has become popular among some textile tech- nologists to view the subject area as yarn engineering, since there are various yarn structures that, with the blending of different fiber types, enable yarns to be con- structed to meet specific end uses. It is therefore necessary for the yarn engineer to have knowledge of the principal routes of material preparation and of the various modern spinning techniques. These topics are covered in this book. A distinction is made between the terms spinning method and spinning technique by referring to a technique as an implementation of a method, and thereby classifying the many techniques according to methods. The purpose is to try to get the reader to identify commonality between spinning systems, something that the author has found useful in carrying out research into new spinning techniques. With any mass-produced product, one essential requirement is consistency of properties. For yarns, this starts with the chosen fiber to be spun. The yarn technol- ogist has to understand the importance of the various fiber properties used in spec- ifying raw materials, not just with regard to the relation of fiber properties to yarn properties, but especially with respect to the effect of fiber properties on processing performance and yarn quality. These aspects are given careful consideration in various chapters throughout the book. An understanding of the meaning yarn quality is seen to be essential; therefore, some effort is devoted to explaining the factors that govern the concept of yarn quality. Textile designers prefer to use the term yarn design rather than yarn engineering, since the emphasis is often on the aesthetics imparted to the end fabric as opposed to any technical function. Fancy or effect yarns, blends of dyed fibers of different colors, and the plying together of yarns are important topics in yarn design, and the principles and processes employed are described in this book. The material presented is largely that delivered over many years of lecturing and is arranged to be suitable for readers who are new to the subject as well as those who are familiar with the technology and may wish to use this book as a reference source. A basic knowledge of physics and mathematics will be helpful to the reader, but is not essential, since a largely descriptive approach has been taken for the © 2003 by CRC Press LLC majority of the chapters. The few chapters that may be considered more mathemat- ically inclined present a more detailed consideration to a particular topic and should be easily understood by anyone who has studied physics and mathematics at the intermediate level. Chapter 1 gives a suitable introduction to the subject area by outlining much of the basic concepts and discussing what technically constitutes a spun yarn. Chapters 2, 3, 5, 6, 7, and 9 should cover most topics studied by technology students up to graduate level, and Chapter 9 collates material that has been delivered as a module component largely to design students. Chapters 4 and 8, and some areas of Chapter 6 that deal with yarn structure-property relation, have been used as topics within a Masters-level module. Although, at the advanced level of study, programs are mainly based on current research findings, some areas of the earlier chapters may prove useful for conversion candidates. Throughout the book, definitions are used, where appropriate, in an attempt to give the reader a snapshot of a particular technical point or topic, which is then explained in greater detail. It is said that a picture is worth a thousand words, and in dealing with technical concepts, this is a truism. The reader will find, therefore, that effort has been given to fully illustrating the substance of each chapter, and the author hopes that this makes the book a pleasant read for you. © 2003 by CRC Press LLC Author Carl Lawrence, B.Sc. (Applied Physics), Ph.D., is Professor of Textile Engineering at the University of Leeds and was previously a Senior Lecturer at the University of Manchester Institute of Science and Technology. Before joining academia in 1981, he worked for 11 years in industrial R&D. Many of these years were with the former Shirley Institute, now the British Textile Technology Group (BTTG). In 2002, he was awarded The Textile Institute’s Warner Memorial Medal for his contributions to investigations in textile technology — in particular, unconventional spinning systems. He is the author of many research papers in the field of yarn manufacture and has several patents in the area of open-end spinning. © 2003 by CRC Press LLC Acknowledgments I wish to express my appreciation to the many companies and individuals who gave me advice, encouragement, and assistance in completing this demanding but enjoy- able project. A special “thank you” to my research colleague and friend Dr. Moham- med Mahmoudhi for his time and effort in preparing the majority of the diagrams in this book. The following companies provided me the opportunity to include many of the illustrations depicted, for which I am very grateful: Andar ADM Group Ltd. Befama S.A. Crosrol Ltd. ECC Ltd. Fehrer AG Fleissener GmbH & Co. Fratelli Mazoli & Co. SpA. Houget Duesberg Bosson Marzoli Melliand Pneumatic Conveyors Ltd. Repco ST Rieter Machine Works Ltd. (Machinenfabrik Rieter) Rolando Macchine Tessili Rolando-Beilla Saurer-Allma GmbH Savio Macchine Tessili SpA. Spindelfabrik Suessen The Textile Institute (Journal of the Textile Institute) TRI (Textile Research Journal) Trutzschler GmbH & Co. KG W. Schlafhorst AG & Co. William Tatham Ltd. Zellweger Uster Zinser C. A. Lawrence University of Leeds © 2003 by CRC Press LLC Table of Contents Chapter 1 Fundamentals of Yarns and Yarn Production 1.1 Early History and Developments 1.2 Yarn Classification and Structure 1.2.1 Classification of Yarns 1.2.2 The Importance of Yarns in Fabrics 1.2.3 A Simple Analysis of Yarn Structure 1.2.3.1 The Simple Helix Model 1.3 Yarn Count Systems 1.3.1 Dimensions of a Yarn 1.4 Twist and Twist Factor 1.4.1 Direction and Angle of Twist 1.4.2 Twist Insertion, Real Twist, Twist Level, and False Twist 1.4.2.1 Insertion of Real Twist 1.4.2.2 Twist Level 1.4.2.3 Insertion of False Twist 1.4.3 Twist Multiplier/Twist Factor 1.4.4 Twist Contraction/Retraction 1.5 Fiber Parallelism 1.6 Principles of Yarn Production 1.7 Raw Materials 1.7.1 The Global Fiber Market 1.7.2 The Important Fiber Characteristics and Properties for Yarn Production 1.7.2.1 Cotton Fibers 1.7.2.1.1 Fiber Length (UHM) 1.7.2.1.2 Length Uniformity Index (LUI) 1.7.2.1.3 Fiber Strength 1.7.2.1.4 Micronaire 1.7.2.1.5 Color 1.7.2.1.6 Preparation 1.7.2.1.7 Leaf and Extraneous Matter (Trash) 1.7.2.1.8 Stickiness 1.7.2.1.9 Nep Content 1.7.2.1.10 Short Fiber Content (SFC) 1.7.2.2 Wool Fibers 1.7.2.2.1 Fineness 1.7.2.2.2 Fiber Length Measurements 1.7.2.2.3 Tensile Properties 1.7.2.2.4 Color 1.7.2.2.5 Vegetable Content, Grease, and Yield © 2003 by CRC Press LLC 1.7.2.2.6 Crimp, Bulk, Lustre, Resilience 1.7.2.2.7 Medullation 1.7.2.3 Speciality Hair Fibers 1.7.2.3.1 Mohair 1.7.2.3.2 Types of Fleeces 1.7.2.3.3 Physical Properties 1.7.2.3.4 Cashmere 1.7.2.3.5 Physical Properties 1.7.2.4